Displacement from start of window to target buffer (nonnegative integer).

target_count

Number of entries in target buffer (nonnegative integer).

target_datatype

Data type of each entry in target buffer (handle).

win

Window object used for communication (handle).

OUTPUT PARAMETER

IERROR

Fortran only: Error status (integer).

DESCRIPTION

MPI_Put transfers origin_count successive entries of the type specified by origin_datatype, starting at address origin_addr on the origin node to the target node specified by the win, target_rank pair. The data are written in the target buffer at address target_addr = window_base + target_disp x disp_unit, where window_base and disp_unit are the base address and window displacement unit specified at window initialization, by the target process.

The target buffer is specified by the arguments target_count and target_datatype.

The data transfer is the same as that which would occur if the origin process executed a send operation with arguments origin_addr, origin_count, origin_datatype, target_rank, tag, comm, and the target process executed a receive operation with arguments target_addr, target_count, target_datatype, source, tag, comm, where target_addr is the target buffer address computed as explained above, and comm is a communicator for the group of win.

The communication must satisfy the same constraints as for a similar message-passing communication. The target_datatype may not specify overlapping entries in the target buffer. The message sent must fit, without truncation, in the target buffer. Furthermore, the target buffer must fit in the target window. In addition, only processes within the same buffer can access the target window.

The target_datatype argument is a handle to a datatype object defined at the origin process. However, this object is interpreted at the target process: The outcome is as if the target datatype object were defined at the target process, by the same sequence of calls used to define it at the origin process. The target data type must contain only relative displacements, not absolute addresses. The same holds for get and accumulate.

NOTES

The target_datatype argument is a handle to a datatype object that is defined at the origin process, even though it defines a data layout in the target process memory. This does not cause problems in a homogeneous or heterogeneous environment, as long as only portable data types are used (portable data types are defined in Section 2.4 of the MPI-2 Standard).

The performance of a put transfer can be significantly affected, on some systems, from the choice of window location and the shape and location of the origin and target buffer: Transfers to a target window in memory allocated by MPI_Alloc_mem may be much faster on shared memory systems; transfers from contiguous buffers will be faster on most, if not all, systems; the alignment of the communication buffers may also impact performance.

FORTRAN 77 NOTES

The MPI standard prescribes portable Fortran syntax for the TARGET_DISP argument only for Fortran 90. FORTRAN 77 users may use the non-portable syntax

INTEGER*MPI_ADDRESS_KIND TARGET_DISP

where MPI_ADDRESS_KIND is a constant defined in mpif.h and gives the length of the declared integer in bytes.

ERRORS

Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ functions do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will be used to throw an MPI:Exception object.

Before the error value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.